With the appeal of energy saving, environmental protection, etc., the market share of LCD device(s) using a light emitting diode (LED) as a back light source is rapidly increased in the market year by year. At present, a common LED back light mainly comprises edge type LED back light and direct type LED back light. In the edge type LED back light, a light guide plate is used, a specific light coupling distance is set between the light guide plate and a LED light emergent surface, and the light guide plate is required to be positioned. As shown in FIG. 1, the common mode is that metal riveted nut stud(s) is used for fixing. However, if the module suffers high impact force in the transportation process or the light guide plate fiercely impacts on the metal riveted nut stud(s), because of poor impact resistance of PMMA for making the light guide plate, cracks easily occur on partial light guide plate, which have an influence on the display quality.